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            <h2 class="title" style="clear: both"><a id="stl_memory_mgmt"></a>Dbstl memory management</h2>
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            <span class="sect2">
              <a href="stl_memory_mgmt.html#id1602244">Freeing memory</a>
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            <span class="sect2">
              <a href="stl_memory_mgmt.html#id1602395">Type specific notes</a>
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              <h3 class="title"><a id="id1602244"></a>Freeing memory</h3>
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        <p>
        When using dbstl, make sure memory allocated in the heap is
        released after use.  The rules for this are:
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              <p>
            dbstl will free/delete any memory allocated by dbstl itself.
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            You are responsible for freeing/deleting any memory allocated by your code outside of dbstl. 
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              <h3 class="title"><a id="id1602395"></a>Type specific notes</h3>
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                <h4 class="title"><a id="id1602915"></a>DbEnv/Db</h4>
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          <p>
        When you open a <code class="classname">DbEnv</code> or <code class="classname">Db</code> object using
        <code class="methodname">dbstl::open_env()</code> or <code class="methodname">dbstl::open_db()</code>, you
        do not need to delete that object. However, if you new'd that object and then opened it
        without using the <code class="methodname">dbstl::open_env()</code> or
        <code class="methodname">dbstl::open_db()</code> methods, you are responsible for deleting the
        object.
    </p>
          <p>
        Note that you must <code class="literal">new</code> the <code class="classname">Db</code> or
        <code class="classname">DbEnv</code> object, which allocates it on the heap. You can not allocate it
        on the stack. If you do, the order of destruction is uncontrollable, which makes dbstl
        unable to work properly.
    </p>
          <p>
        You can call <code class="function">dbstl_exit()</code> before the process exits, to release any
        memory allocated by dbstl that has to live during the entire process lifetime. Releasing the
        memory explicitly will not make much difference, because the process is about to exit and so
        all memory allocated on the heap is going to be returned to the operating system anyway. The
        only real difference is that your memory leak checker will not report false memory leaks.
    </p>
          <p>
        <code class="function">dbstl_exit()</code> releases any memory allocated by dbstl on the heap.  It
        also performs other required shutdown operations, such as closing any databases and
        environments registered to dbstl and shared across the process.
    </p>
          <p>
        If you are calling the <code class="function">dbstl_exit()</code> function, and your
        <code class="classname">DbEnv</code> or <code class="classname">Db</code> objects are new'd by your code,
        the <code class="function">dbstl_exit()</code> function should be called before deleting the
        <code class="classname">DbEnv</code> or <code class="classname">Db</code> objects, because they need to be
        closed before being deleted.  Alternatively, you can call the
        <code class="methodname">dbstl::close_env()</code> or <code class="methodname">dbstl::close_db()</code>
        functions before deleting the <code class="classname">DbEnv</code> or <code class="classname">Db</code>
        objects in order to explicitly close the databases or environments. If you do this, 
        can then delete these objects, and then call <code class="function">dbstl_exit()</code>.
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              <div>
                <h4 class="title"><a id="id1602901"></a>DbstlDbt</h4>
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          <p>
        Only when you are storing raw bytes (such as a bitmap) do you have to
        store and retrieve data by using the <code class="classname">DbstlDbt</code> helper class. Although you
        also can do so simply by using the Berkeley DB <code class="classname">Dbt</code> class, the 
        <code class="classname">DbstlDbt</code> class offers more convenient memory management behavior.
    </p>
          <p>
        When you are storing <code class="classname">DbstlDbt</code> objects (such as
        <code class="classname">db_vector&lt;DbstlDbt&gt;</code>), you <span class="emphasis"><em>must</em></span> allocate
        heap memory explicitly using the <code class="function">malloc()</code> function for the
        <code class="classname">DbstlDbt</code> object to reference, but you do not need to free the memory
        – it is automatically freed by the <code class="classname">DbstlDbt</code> object that owns it
        by calling the standard C library <code class="function">free()</code> function.
    </p>
          <p>
        However, because dbstl supports storing any type of object or primitive data, it is rare
        that you would have to store data using <code class="classname">DbstlDbt</code> objects while using
        dbstl.  Examples of storing <code class="classname">DbstlDbt</code> objects can be found in the
        <code class="methodname">TestAssoc::test_arbitrary_object_storage()</code> and
        <code class="methodname">TestAssoc::test_char_star_string_storage()</code> functions, which are
        available in the dbstl test suite.
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